Pneumatic pump



June 1961 D. STATHAM PNEUMATIC PUMP Filed Jan. 19, 1959 JNVENTOR. LOUISD. STATHAM ATTOQNEYS United States Patent 2,989,227 PNEUMATIC PUMP LouisD. Statlram, Beverly Hills, Califi, assignor to Statham Instruments,Inc., Los Angeles, Calif., .a corporation of-California FiledJan. 19,1959, Ser. No. 787,421 2 Claims. (Cl. 230-1) This invention relates topneumatic pumps, and is particularly concerned with a hand typepneumatic pump designed to be easily operated for inflating aninflatable member with air.

When employing conventional pneumatic hand pumps 'for inflatinginflatable articles with air, e.g., bicycle tires, air mattresses, andthe like, after a certain amount of air has been pumped into the articleand before it has become fully inflated, the back pressure rises to apoint Where considerable force is required to pump additional air intothe article to complete its inflation to the desired extent.

It 'is an object of this invention to provide a pneumatic hand pumphaving means embodied therein to minimize the force required to completeinflation of an inflatable article after the article has been partiallyinflated.

A still further object is to afford a pneumatic hand pump of theaforementioned character which is easily and relatively inexpensivelymanufactured.

The above objects are accomplished by providing a pneumatic hand pump inwhich the piston is removable and replaceable with an adapter whichfitsinto the cylinder. The adapter is in the form .of an elongated hollowmember which can be positioned axially within the cylinder and has aninternal diameter substantially less than the internal diameter of thecylinder. A piston having a diameter about equal to that of the internaldiameter of the adapter is mounted for slidable movement in the adapter.7 7

Thus, when an article is to be inflated, the conventional large pistonis employed in the pump cylinder until the back pressure generatedraises the force required to operate the piston to a value when itbecomes tiresome to manually operate the pump. The conventional pistonis removed, and the aforementioned adapter with its smaller cooperatingpiston is incorporated in the pump cylinder. Due to the substantiallydecreased area of the smaller piston as compared to the large pistonwhich was removed, a correspondingly smaller force is required tooperate the piston, thus making it much easier to pump the remaining airinto the article to fully inflate same.

The invention will be more clearly understood from the followingdescription of a preferred embodiment taken in connection with theaccompanying drawing, wherein:

FIG. 1 is a section of the pump employing therein the conventional typeof piston;

FIG. 2 is the pump of FIG. 1 with the conventional piston replaced bythe adapter and smaller piston of the invention;

FIG. 3 is a sectional view of the adapter;

FIG. 4 is a section taken on line 44 of FIG. 2;

FIG. 5 is an enlarged section of the valve of FIG '1;

FIG. 6 is a view taken on line 6-6 of FIG. 5; and

FIG. 7 is a sectional detail, partly in elevation, of the rod and pistonstructure of FIG. 1.

Numeral 10 represents the pump cylinder which is closed at its forwardend by an end member 12 threaded at 12 over the end of the cylinder, asealing gasket 13 being provided between the end of the cylinder and theend member 12. The opposite end of the cylinder Patented June 20, 1961is closed by a cap 14 threaded into the end of the-cylinder at 16.

A-piston 18 is positioned for slidable movement in cylinder 10 by meansof a rod 20 connected to the center of the piston, the rod beingslidably received in an aperture 22 in the end cap 14, and having ahandle 24 connected to its outer end exteriorly of cylinder 10. Thepiston 18 is composed of a flexible disc 26 of a diameter about equal toor slightly greater than the internal diameter of the bore 28 of thecylinder. The disc 26 is clamped between a washer 30 and a washer 32,and supported on rod 20 by means of a stud 34 which is threaded at 36into a bore 37 of rod 20. A bolt 38 is threaded into the lower end ofstud 34, which passes through the center of washer 30 and dis-c 26 andabuts washer 32. The bolt 38 passes through the center of washer 32, andthus washers 30 and 32 and the disc 26 are clamped as a unit between thelower end of rod 20 and the head 40 of bolt 38, as seen in FIG. 7.

-A-spring 42 is carried at the lower end of rod 20 and resting on washer30 to act as a shock absorber and make contact with end cap 14 onreverse stroke when disc 26 is drawn upward, as seen in FIG. 1. A spring44 mounted about rod 20 in a housing 46 on cap 14, acts as a shockabsorber and makes contact with the ring 48 at the base of handle 24,when the piston 26 is pushed downward, as seen in FIG. 1.

End member 12 carries a depending housing 50 which threads into theend-52 of a hose 54. Housing 50 carries a ball check valve 55comprising'a support 56 threaded into housing 50, said support having acentral aperture 58. A spring 60 rests on support '56 and mounts a ball61 at its upper end which is normally urged against a seat 62 formed atthe periphery of an aperture 63 in end member 12. A groove 59 is formedin the lower surface of the member 56 for adjusting the position"thereof and the compression of spring 60.

' It will thus be seen that when piston 26 is pushed down toward endmember 12, the air in the forward portion 64 between piston 26 and endmember 12 will be forced out through valve 55 and via hose 54 which isconnected to an article being inflated (not shown), but air cannot passfrom hose 54 back into the cylinder 10. The disc 26 forming the pistonis in tight engagement with the wall of cylinder 10 on the downstroke,but on the upstroke air from the upper portion 65 of cylinder 10 willleak past the outer periphery of disc 26 into the lower portion 64 ofcylinder 10 to be compressed and forced through valve 55 on thedownstroke as above described. The slidable fit between rod 20 and theaperture 22 in end cap 14 provides sufiicient clearance for air to leakthrough the aperture 22 into the upper portion 65 of cylinder .10 toprovide the air which is to be subsequently compressed and pumpedthrough hose 54.

Now when the force required to operate piston 26 increases as result ofback pressure, to a point where it becomes tiresome to push rod 20, theend cap 14 is removed together with rod 20 and piston 26, and this unitis replaced by a unit 66. Unit 66 is composed of an adapter 70 in theform of an elongated hollow member having bell shaped outer ends 71 and72 and an intermediate portion 73 having an internal diametersubstantially smaller than bore 28 of cylinder 10. The diameter at theouter ends of the bell shaped members is about the same or slightlygreater than that of bore 28 so that these members fit tightly intocylinder 10, but with insufficient friction so that the adapter 70 canbe slid down into the cylinder 10, with the end 72 of the adapterdisposed against the seal 13. The upper end 71 of the adapter abuts aseal 74 positioned in a peripheral recess in the lower surface of endcap 75 which is threaded into the upper end of cylinder 10.

A flexible disc 76 forming a piston is mounted for slidable movementwithin the intermediate portion 73 of reduced diameter of adapter 70.The disc 76 is mounted on a rod 77 in a manner similar to the mountingof disc 26 on rod 20. The rod 77 carries a ring 78 on which is seated aspring 79 which is adapted to make contact with end cap 75 on theupstroke. Rod 77 slidably passes through an aperture 80 in cap 75, and aspring 80' is mounted in a housing 81 on cap 75, to make contact with aring 82 mounted at the base of a handle 83 to prevent shock at the endof the downstroke of rod 77. The stops provided by contact of spring 79and end cap 75 on the upstroke, and by spring 80 and ring 82 on thedownstroke are positioned so that disc 76 is always located in theintermediate portion 73 of adapter 70, and at no time enters the bellshaped end portions 71 or 72 of the adapter.

It will thus be seen that when the adapter unit 70 and its associatedmechanism including piston 76, rod 77 and handle 83 are incorporatedinto cylinder in place of cylinder 26 and its associated structure,since the piston 76 has a substantially smaller area than piston 26, amuch smaller force is required to continue the pumping of air into thearticle partially inflated using piston 26. On the upstroke, air leakspast the periphery of piston 76 from the space above piston 76 to thespace below it, and air is furnished to the upper portion of the adapterabove piston 76 by leakage through aperture 80, as in FIG. 1.

While I have described a particular embodiment of my invention for thepurpose of illustration, it should be understood that variousmodifications and adaptations thereof may be made within the spirit ofthe invention as set forth in the appended claims.

I claim:

1. A pneumatic hand pump which comprises a hollow cylinder closed at itsfront end, a removable closure at its rear end, a removable adapter inthe form of an elongated hollow member positioned axially in said cylin.

der, said adapter being removable through said rear end of saidcylinder, said adapter being bell shaped at its opposite ends, theopposite ends of said cylinder being closed, the bell shaped ends ofsaid adapter being positioned adjacent the opposite ends of saidcylinder, the outer diameter of said bell shaped end portions beingabout the same as the internal diameter of said cylinder, so that saidbell shaped end portions frictionally engage the opposite internalsurfaces of said cylinder to maintain said adapter in axial position insaid cylinder, the internal diameter of said adapter intermediate thebell shaped end portions being substantially less than the internaldiameter of said cylinder, a piston having a diameter about equal to theinternal diameter of said adapter and mounted therein for slidablemovement axially of said cylinder, a rod connected to said piston formovement thereof, said rod slidably received in the rear closure of saidcylinder, with suflicient clearance to permit air to pass into saidcylinder and a check valve in the front end of said cylinder for passageof air from the forward end of said adapter in front of said pistonoutwardly through said valve.

2. A pneumatic hand pump as defined in claim 1, wherein said piston,adapter and closure are adapted to be replaced by a closure and pistonassembly, the latter being of such size as to slidably engage saidcylinder.

References Cited in the file of this patent UNITED STATES PATENTS753,530 Ten Eyck Mar. 1, 1904 767,526 Paulson Aug. 16, 1904 767,527Paulson Aug. 16, 1904 1,019,507 McCormick Mar. 5, 1912 1,263,401 FraserApr. 23, 1918 1,267,635 Cox May 28, 1918 1,794,356 Baker Mar. 3, 19312,163,885 MacClatchie et a1 June 27, 1939 2,686,090 Leman Aug. 10, 19542,759,329 Ponti Aug. 21, 1956 2,880,043 Landis Mar. 31, 1959

